How do I photograph people in front of an LED wall without banding or badly exposed faces?
Asked 4/15/2016
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2 answers
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I need to photograph an interactive LED wall with people standing in front of it. My main problems are:
- avoiding banding/flicker or dark horizontal lines from the wall’s refresh rate
- avoiding moiré from the LED pixel pattern
- keeping the wall visible without underexposing the people, or blowing out the wall
I’m using a Nikon D4 or D7200, with a wide lens, and I don’t need to freeze all motion but can’t have excessive blur. I’m wondering about the best approach for shutter speed, aperture, ISO, and whether fill flash would help.
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
10y ago
2 Answers
3
You have diferent issues here. Lets separate them.
1) You have a bright wall and dark people... It is the same case as if you have a bright window with people on an interior. Your options are limited.
Use aditional ilumination, like firing a flash as fill light. If you are shooting from far away this could not work. But if you have permissions you can use some asistants closer to the scene and remote triggers to light up the scene.
Correct in post production leveling up the dark zones or some Hdri technique. Shooting in Raw is required.
2) The "flickering" Lets get technical. A video has an intrinsec "strobe" component, a frame, then another frame. A monitor can have (or not) a refresh rate. The lcd fluorescent panels have it, and some led panels have it to dim the intensity of the light.
If you photograph that at a shutter speed lower or too close than thoose refresh rates you can have a flicker. So you need to use a shutter speed 2 or 3 times below that refresh rate. Lets think a panel has a refresh rate of 60 Hz. Then you need to shoot at lets say 1/30 or 1/15. Make some tests on your home computer, television, and the kitchen lights.
3) The moire.
You have a problem here. You can try for example focus at the closer objects so the panel is a little blurry. Use a wide aperture.
Try a "fog" filter, or a star filter in your lens. You can try a DIY aproach for example using some vaseline in an UV filter.
Originally by user37321. Source · Licensed CC BY-SA 4.0
user37321
10y ago
0
Generated from our catalog & community — verify before relying on it.
Treat this as two separate problems: exposure balance and LED artifacts.
For exposure, the LED wall is like a bright window behind darker subjects. If you want both the wall and faces visible, add light to the people if possible. Fill flash can help, especially from an angle to light faces without reflecting strongly off the wall. If flash isn’t practical, shoot RAW so you have the most latitude for recovering shadows/highlights in post.
For banding/flicker, the issue is usually the wall’s refresh or scan rate interacting with shutter speed. A longer shutter speed often helps; around 1/30 s can work better than faster speeds, though you’ll need to balance that against subject blur.
For moiré, slightly reducing fine detail helps. A shallow depth of field can blur the LED array a bit if you focus on the people, and stopping down very far can also reduce moiré through diffraction, though that may not be ideal for low light.
So: prioritize focus on faces, use the slowest shutter you can tolerate for motion, add fill light if allowed, and shoot RAW for post correction.
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